Statistical machine translation

#Machine translation (MT) is the automatic translation, for example, using a computer system, from a first language (a “source” language) into another language (a “target” language). Systems that perform an MT process are said to “decode” the source language into the target language. From an end-user's perspective, the MT process is relatively straight-forward. The MT process receives as input a source sentence (or “string” of words) and after processing the input sentence, outputs a translated sentence in the target language.

#One type of MT process is referred to as a statistical MT decoder. Conventional statistical MT decoders may include a language model (LM) and a translation model (TM).

#According to an aspect of this invention, a method includes detecting a syntactic chunk in a first string in a first language, assigning a syntactic label to the detected syntactic chunk in the first string, aligning the detected syntactic chunk in the first string to a syntactic chunk in a second language string, said aligning based on the assigned syntactic label, and translating each word from the first string into a second word corresponding to a possible translation in the second language.

#FIG. 1 is a flowchart of a linguistic statistical translation (LST) process.

#FIG. 2 illustrates an exemplary source and target sentence.

#FIG. 3 illustrates a sentence-level chunk reordering table corresponding to the sentences of FIG. 2.

#A statistical MT system as described herein may be modeled as three separate parts: (1) a language model (LM) that assigns a probability P(e) to any target string of words, (2) a translation model (TM) that assigns a probability P(f|e) to any pair of target and source strings, and (3) a decoder that determines translations based on the assigned probabilities of the LM and TM.

#A conventional MT system may translate source sentences into target sentences by making a series of word-based decisions. The word-based decisions may include a translation decision where each source word is translated to a target word. A mapping (“alignment”) decision may also be performed for each translated word, e.g., mapping multiple source words to a single target word-based on a determined fertility of the translated source word. A rearrangement (“distortion”) decision may also be performed, e.g., re-arranging the order of words from a source sentence to translated words in the corresponding target sentence. The translation, mapping and distortion decisions are based on weighted probabilities determined during the translation process.

#Some source sentences pose translational challenges that are not handled well by conventional word-based MT systems. For example, translational challenges include the translation of phrases, restructuring sentences for syntactical reasons, and translations of non-adjacent words into single words or phrases in the target sentence.